ML14231A067

Meeting Slide for Watts Bar Nuclear Plant, Unit 1 Tpbar Loading Increase LAR Pre-Submittal Meeting

ML14231A067
Person / Time
Site:	Watts Bar
Issue date:	08/11/2014
From:	Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation
Lingam S
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ML14231A129	List: ML14231A067 ML14231A072
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Download: ML14231A067 (11)

Text

8/11/2014 Watts Bar TPBAR Loading Increase LAR PreSubmittal Meeting Nuclear August 14, 2014 Introduction Nuclear

• Purpose of Meeting

- Update NRC Management on TVAs Plan to Submit a License Amendment Request (LAR) in January 2015 to Increase Allowable TPBAR Loading for Watts Bar Unit 1 2

1

8/11/2014 Agenda Nuclear

• Introduction Jim Lemons

• Background Mark Burzynski

• DOE TPBAR Loading Plans Carla Borrelli

• Tritium Permeation Experience Cheryl Thornhill

• Projected Pathway Exposures Mark Burzynski

• Plant Modifications Carla Borrelli

• PostLOCA Shutdown Margin Analysis Mark Burzynski

• Licensing Plan and Schedule Mark Burzynski

• Closing Comments Jim Lemons 3

Background

Nuclear

• Background

- License Amendment 40 Issued on September 23, 2002 Authorized Loading Up to 2304 TPBARs

• Allowed Loading Subsequently Reduced to Address Post LOCA Shutdown Margin Issues

- TVA Letter Dated March 22, 2005 Notified NRC of Interim Cumulative TPBAR Tritium Release Limits

• While Higher than Projected Permeation Rates were Investigated

- License Amendment 77 Issued on May 4, 2009 Authorized Loading Up to 704 TPBARs 4

2

8/11/2014 DOE TPBAR Loading Plans Nuclear

• DOE TPBAR Loading Plans for Watts Bar Unit 1:

Cycle Date TPBAR Loading Tech Spec Limit C12 October 2012 544 704 C13 April 2014 704 704 C14 October 2015 704 704 C15 March 2017 1104 1792*

C16 October 2018 1504 1792*

C17 April 2020 1792 1792*

• Proposed 5

Tritium Permeation Nuclear Experience (1/2)

• TVA and PNNL Performed Surveillance Of Estimated Tritium Permeation Over Last 7 Cycles of TPBAR Irradiation for the Tritium Readiness Program.

- Permeation Was Higher than Original Design Goal, But No Design or Production Flaws Have Been Identified.

Uncertainty bars represent 90%

confidence interval 6

3

8/11/2014 Tritium Permeation Nuclear Experience (2/2)

• Original Functional Requirement for TPBAR Tritium Permeation in Cycle 6 was an Average of 1 Ci/TPBAR/Year.

• Radionuclide Releases to Environment at WBN1 will be Managed to Meet NRC Requirements in 10 CFR Part 20 and 10 CFR Part 50 Appendix I.

- Proposed Management Strategy Assumes TPBAR Tritium Permeation will be 5.0 Ci/TPBAR/year.

7 Projected Pathway Exposure (1/2)

Nuclear

• FSAR Chapter 11 Radiological Consequence Analyses Will Be Based on:

- Release Source Term Based on NRC NUREG0017 Methodology to Calculate an Average Maximum Hypothetical Release

- TPBAR Loading of 1792 TPBARs

- TPBAR Tritium Permeation Rate of 5 Curies/TPBAR/Year (Based on Conservative Upper Bound of Plant Data)

- Use of TVA QA Computer Codes GELC and QWATA to Calculate Dose to Maximum Exposed Offsite Individual 8

4

8/11/2014 Projected Pathway Exposure (2/2)

Nuclear

• Projected Pathway Exposures to Maximum Hypothetical Individual Remain Below NRC Regulatory Limits for All Cases.

Pathways Preliminary Projected Doses NRC Limit Liquid (Realistic) 0.75 mrem Total Body 3 mrem Liquid (Design) 0.81 mrem Total Body 1.29 mrem Total Body 10 mrem Gaseous (Realistic) 10.86 mrem Critical Organ 15 mrem 1.29 mrem Total Body 10 mrem Gaseous (Design) 11.34 mrem Critical Organ 15 mrem

• Applicable NRC Requirements (10 CFR Part 20 and 10 CFR Part 50 Appendix I) and Technical Specifications Will Be Met for All Cases.

9 Preliminary Results Based on 1700 TPBARs Plant Modifications (1/2)

Nuclear

• Addition of 500,000 Gallon Tritiated Water Tank System

- Increase Flexibility to Manage RCS Feed and Bleed Under Contingency Scenarios and Time Effluent Releases to Environment

- Allows Changes to Operating Strategy for RCS Feed and Bleed to Keep Tritium Concentrations Low and Simplify Occupational Exposure Controls

- Implemented under 10 CFR 50.59 10 5

8/11/2014 Plant Modifications (2/2)

Nuclear

• Replace Check Valves Used for Thermal Relief on CCS and ERCW Supply Lines with Relief Valves

- Eliminates PostLOCA Manual Operator Actions for Isolation

• Previously Approved by NRC in License Amendment Issued on March 29, 2004

- Eliminates 40 GPM Source of Unborated Water Leakage into Containment (Assumed for 16 Hours)

- Implemented under 10 CFR 50.59 11 PostLOCA Shutdown Nuclear Margin Analysis (1/5)

• PostLOCA Reactivity Analysis will Be Consistent with Previously Approved by NRC for License Amendment 77 with the Following Key Changes:

- Elimination of Dilution of Sump Water from 40 GPM Unborated Water InLeakage

- Reduce Required RCS Boron Concentration by Increased IFBA Loading

- Modification of Simplified Assumptions on TPBAR Lithium Leaching

• Time Dependent Leaching Rate Used

• Preliminary Results Show Sufficient Shutdown Margin for 1792 TPBARs 12 6

8/11/2014 PostLOCA Shutdown Nuclear Margin Analysis (2/5)

• Xenon Free PostLOCA - RSAC Item 3.16B PreLOCA Cb PostLOCA Cb Design Margin (ppm) (ppm) Limit (ppm)

(ppm)

HFP EQXE Cb = 744 ppm 1792 TPBARs 644 1923.0 2135.3 212.3

Conclusion:

744 ppm core with 1792 TPBARs can accommodate cycle variations Preliminary Results 13 PostLOCA Shutdown Nuclear Margin Analysis (3/5)

• Hot Leg Switchover - RSAC Item 3.16A PreLOCA Cb PostLOCA Cb Design Margin (ppm) (ppm) Limit (ppm)

(ppm)

HFP EQXE Cb = 744 ppm 1792 TPBARs 644 1607.0 1736.5 129.5

Conclusion:

1792 TPBAR core at 744 ppm with time dependent leach rate meets requirements Preliminary Results 14 7

8/11/2014 PostLOCA Shutdown Nuclear Margin Analysis (4/5)

• ColdLeg Recirculation - RSAC Item 3.11B PreLOCA Cb PostLOCA Cb Design Margin (ppm) (ppm) Limit (ppm)

(ppm)

HFP EQXE Cb = 744 ppm 1792 TPBARs 644 1817.0 2041.2 224.2

Conclusion:

1792 TPBARs at 744 ppm core meets requirements.

Preliminary Results 15 PostLOCA Shutdown Nuclear Margin Analysis (5/5)

• Reflood Recriticality - RSAC Item 3.11C PreLOCA Cb Intermediate Small LBLOCA (ppm) LBLOCA (Keff)

(Keff)

HFP EQXE Cb = 744 ppm 1792 TPBARs 644 0.976000 0.993956

Conclusion:

1792 TPBAR core at 744 ppm with time dependent leach rate meets requirements.

Preliminary Results 16 8

8/11/2014 Licensing Activities Nuclear

• License Amendment Request to Support Tritium Production Requirements

- Update of PostLOCA Reactivity Analysis Previously Approved by NRC for License Amendment 77

- Would Include Discussion of Expected Effluent Releases (Using Realistic Source Term) and Radwaste System Design and Station Dose (Using Design Basis Source Term) for 1792 TPBARs 17 Technical Specification Changes Nuclear

• Technical Specification (TS) Change to New TPBAR Limit

- Revise TS 4.2.1 to Reflect New Upper Limit of 1792 on TPBAR Loading

- Delete Outdated TPBAR Information in Surveillance Requirements 4.5.1.4 and 4.5.4.3 18 9

8/11/2014 Licensing Activities Schedule Nuclear 19 Closing Nuclear

• TVA Plans to Submit a License Amendment Request for 1792 TPBARs in January 2015

- Supporting Analyses will Bound Operating Experience with Tritium Permeation

- Supporting Analyses will Reflect Plant Modifications Made to Increase Margins

- All Regulatory Requirements and Plant Technical Specifications will be met with 1792 TPBAR Core Design 20 10

8/11/2014 Nuclear Questions 21 11